The invention relates to a perforating, grooving or punching apparatus for multi-color or single color sheet-fed rotary presses.
Multi-color sheet-fed rotary presses comprise several printing and/or varnishing units, each of which is equipped with a rubber cylinder and an appertaining holding system for a blanket. The utilization of such multi-color, offset printing presses for perforating, grooving or punching of sheets is known in the prior art.
U.S. Pat. No. 3,554,070 which issued to Harry S. Boyd on Jan. 12, 1971 discloses a method of gluing perforation strips on a counter-pressure cylinder of a printing and/or varnishing unit and of using this to perforate a sheet supported by the elastic rubber blanket of the rubber cylinder. In this method the perforation strips must be installed on the poorly accessible and non-removable counter-pressure cylinder so that the tasks are difficult and time consuming. Also the correct position of the perforation strips on the built-in counter-pressure cylinder is difficult to find, so that expensive position corrections of the glued perforation strips before the start of priming are frequently necessary. This results in considerable set-up and installation times.
It is also a disadvantage with the Boyd method that the perforation strips are installed on the counter-pressure cylinder for only one print application and must then be removed once more. All the expenses for long setup and installation times and the costs of perforation strips are incurred again with a later print application with the same perforations.
In addition, the perforation strips press themselves into the rubber blanket of the rubber cylinder and cause abrasion with a negative contour so that such a relatively expensive rubber blanket can no longer be used.
A perforation in combination with a running printing is only possible in a non-printed area, since otherwise arching of the sheet and adhesion to the rubber blanket near the perforation strip occur so that the printing image is damaged. For a perforation in a printed sheet area, drying and an expensive additional passage through the machine is therefore necessary.
Furthermore, every sheet arches disadvantageously near the perforation because of impressions into the yielding rubber blanket so that the sheet output and stacking can be impeded considerably.
Printing presses with counter-pressure cylinders twice the size of rubber cylinders are also known. In these printing presses a double perforation form can be installed at still considerably higher cost, which is no longer economically sound.
Grooving forms cannot be produced by the above-described methods with satisfactory results, especially since printed sheets in particular become badly frayed in the area of the groove because of the yielding support in the rubber blanket.
Furthermore, DE-OS 23 41 326 discloses a method of gluing perforation strips on the rubber blanket of the rubber cylinder to perforate a sheet with this in the direction of the counter-pressure cylinder, whereby the counter-pressure cylinder is covered by a special, removable stretched foil/sheeting. To mount such a special foil/sheeting, foil holding devices are required on the counter-pressure cylinder so that said counter pressure cylinder can be converted from the normal printing process without a sheet to a perforation process with a sheet. The method described here can therefore only be used with presses with suitably equipped counter-pressure cylinders.
It is also a disadvantage here that the perforation form is removed after a print application from a relatively expensive rubber blanket that can normally be re-used and must again be installed for a later possible print application with the same perforation form. Since the perforation strips press into the relatively soft rubber blanket in this case during the perforation process, a print application and a perforation can be carried out with this arrangement in one machine passage only if the perforation can take place in a non-imprinted sheet area.
According to the description, the perforation strips are to be glued on the rubber blanket outside of the machine, i.e. when the blanket has been removed. Installation with the required dimensional precision is hardly possible in practice, since the position of the rubber blanket with the perforation form applied outside of the press can no longer be corrected after assembly in the press, and dimensional deviation of the outer contour of the raised perforation strips with a rubber blanket mounted cylindrically into the machine from the position of the outer contour when the rubber blanket lies fiat occurs. Thus, when attaching perforation strips on a rubber blanket outside the press, at least a rough dimensional precision must be achieved for the perforations, or the position of the perforation strips must be corrected at high cost in the press as in the previously mentioned method, so that no simplification or improvement can be achieved here in this respect.
This process is described especially in combination with a five-cylinder construction of the printing groups, whereby two rubber cylinders interact with a counter-pressure cylinder and wherein particular perforation lines crossing each other are to be attached to a rubber cylinder. This application is restricted to the special five-cylinder. construction.
Treatment profiles in multiple parts are known from the book printing industry in the form of a tint-printing process, and these consist of a first perforation, grooving or punching strip which can be glued on, of a connection layer connected in a detachable manner to same, and a counter-punch strip or counter-grooving strip connected to the former and also being detachable. Such a counter-punch strip or counter-grooving strip is serf-adjusting as it is placed on a counter-pressure plate during the first passage, and for this an adhesive surface with a pull-off protective foil is provided. For the further treatment of the sheets, the connection layer is pulled off and removed. Such perforation, grooving or punching processes are carried out at relatively slow speed in the book printing industry in separate machine passages. The known multi-part treatment profiles used for this have a large cross-section and it has been practically impossible to use them until now in combination with multi-color sheet-fed rotary, presses, in particular because of the yielding support yielding counter stops or the yielding counter-pressure application.
It is an object of the present invention to provide a perforation, grooving or punching device for multicolor sheet-fed rotary presses that will reduce the cost for such sheet treatment. This object is attained by the invention as set forth in claim 1.
According to claim 1 the apparatus of the invention comprises a rectangular base plate made of a flexible and shape-retaining material on which can be stretched in place on a rubber cylinder instead of a rubber blanket by means of the blanket holding system. In addition a rectangular base foil/sheeting is provided which is made of a flexible and shape-retaining material, over which it is possible to stick embossed treatment profiles as perforation, and/or grooving and/or punching profiles corresponding to given perforation and/or grooving and/or punching forms. At least two attachment strips are provided on the base plate at a distance from each other (in the built-in state in the circumferential direction of an appertaining rubber cylinder), preferably in opposed marginal areas of the base plate, and the foil/sheeting can be detachably attached to opposed marginal areas by means of same in a stretched condition.
A great number of improvements and advantages are achieved with such a device:
The base plate can be installed very rapidly and easily instead of a rubber blanket on a rubber cylinder, since the blanket holding system provided on the rubber cylinder on the machine side is designed for rapid and easy replacement. According to claim 2, a base plate is equipped for this purpose advantageously with holding rails on opposed marginal areas, said holding rails corresponding lo those of the rubber blankets for the rotary press model used. To that extent the utilization of the device is possible universally with all current press models in printing and/or varnishing plants. Perforation and/or grooving and/or punching forms can be installed easily and comfortably outside the machine on the punch foil. Thanks to the separable attachment of the punch foil on the base plate which is then fixedly installed on the rubber cylinder, and can combine with the separable attachment, relative position corrections between the base plate and the foil/sheeting and thus position corrections relative to a sheet to be treated, can be carried out easily and rapidly without having to change the forms installed on the punch foil. The person schooled in the art has known means at his disposal for rapidly separable attachment of the punch foil on the base plate. With this method only a very short set-up time is required, e.g. for the conversion of a printing or varnishing group to carry out a perforation, grooving or punching operation.
The base plate should be sufficiently flexible so that it can be stretched cylindrically on the rubber cylinder, but should on the other hand be shape-retaining, especially at its surface, and for this reason a plastic plate is especially well suited according to claim 3. The punch foil lies on such a surface-stable base plate, whereby the surface of the base plate is not impressed or arched during a treatment process and an imprinting on the raised treatment profile, contrary to what happens with a rubber blanket. In this way the treatment goes from a support of the process profile on the relatively hard base plate surface to the counter pressure cylinder which is as a rule also provided with a hard surface. Thus the perforation and punching profiles cut through the presented sheet precisely and without arching of the sheet, so that clean punch and perforation cutting edges of high quality result. To achieve this, merely a simple and precise gap adjustment between the foil/sheeting and the surface of the counter-pressure cylinder is required, with a gap width equal to the profile height of the process profiles. This adjustment can be effected by means of the adjusting device already provided on the machine side. Similarly, clean groove forms can also be adjusted and maintained.
Since treatment takes place between relatively hard supporting surfaces and as a result practically no arching of the sheet takes place, the treated sheets remain plane and smooth as before and can be stacked cleanly and high by means of an automated sheet output. This makes also additional trouble free treatments possible, such as e.g. an additional passage through the press.
In a sheet treatment the foil/sheeting does not come into contact with a sheet surface in the vicinity of a process profile when the gap is adjusted correspondingly. As a result, and because of the precise, cutting-like treatment, perforations and punch-outs, for example can be carried out in one work operation with printing when the printing color has not yet dried, even when the perforations and punches are located in the imprinted area. Thus drying times in additional passages of the sheets through the press can be avoided, so that possibly considerable cost savings can be obtained.
It is a considerable advantage of this device that the foils/sheeting with installed perforation, grooving or punching forms can be archived for later identical print applications. The cost of such archiving is relatively low because economic punch foils/sheeting, e.g. thin, preferably 0.18 mm thick plastic foils can be used according to claim 4. Thus, archiving is possible in particular in a space-saving hanging file.
For subsequent print applications with the same perforation, grooving or punching forms, these no longer have to be built up at great cost. Merely a quick conversion and attachment of the punch foils already available for this is necessary, so that considerable cost savings can be achieved with such subsequent orders. A punch foil with the characteristics of claim 5, treatment profiles can be attached and glued on especially rapidly and precisely. For this purpose the punch foil is provided with a perpendicular grid line arrangement as a registration grid. The grid lines extend preferably in the axial direction of an appertaining rubber cylinder at millimeter distances from each other. Grid lines adjoining each other in the circumferential direction of an assigned rubber cylinder also have equal distances between lines, but these are slightly less than 1 mm. These reduced distances between lines take the fact into account that the outer contour of the raised, glued process profiles extends on a larger cylinder diameter than the outer punch foil surface when the punch foil is stretched cylindrically. These differences do not yel appear when the punch foil lies fiat, when the process foils are glued on. Furthermore, with the above-described reduction of spaces between lines, machine-specific and sheet-specific conditions can also be taken into account in addition to the cylinder diameter differences and projections on a plane grid line arrangement which can be calculated.
For an accurate-to-size attachment of process profiles the procedure consists in measuring out the process form on a printing plate model or a sheet model. The numerical values found by measurement are then transferred into the grid-line arrangement, whereby only the corresponding numerical values and not the measured values are transferred. The corresponding glued process profiles then produce the accurate-to-size process form in the development on the sheet when the punch foil is stretched cylindrically.
The characteristics of claim 6 can be used for rapid and simple attachment of the punch foil on the base plate, whereby the possibility is given to correct the position of the punch foil relative m the base plate. It is proposed for this purpose to attach the fastening strips so as to be capable of displacement relative to the base plate and capable of being fixed, and to connect the punch foil fixedly and separably to the fastening strip. For this connection, alignment pins and assigned punch-outs of the punch foil are used. For a plurality of punch foils in one archive, punch-outs with the same layout must be provided.
According to claim 7, holding strips can also be installed in the marginal areas of the punch foil, and these can then be connected to the fastening strips. Here, too, adjustment zones can be provided between a fastening strip and a holding strip, and in that case the fastening strips could possibly be attached fixedly to the base plate.
A number of arrangements are generally known for such attachments capable of being shifted and fixed. According to claim 8, simple and inexpensive screw and slot connections are used. Depending on conditions, fastening strips in two parts, with one strip part fastened to the base plate and a second strip part movable relative to the first strip can be used and/or holding strips between which the base plate or possibly also the punch foil can be held.